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Symposium 241
Symposium 241
Abstract details
The Nature of the Ubiquitous Nuclear Star Clusters in Spiral Galaxies from HST and VLT spectroscopy
van der Marel, Rossa, Walcher, Boeker, Charlot, Ho, Rix & ShieldsAbstract
It has been found from HST imaging studies that most spiral galaxies host a pronounced "nuclear" star cluster in their very center. To understand the nature of these clusters we obtained spectra with HST/STIS and VLT/UVES of the nuclear clusters in 40 spiral galaxies. To infer the star formation history, metallicity and dust extinction, we fitted weighted sums of single-age stellar population templates to the spectra. The luminosity-weighted age of the clusters ranges from 10 Myrs to 10 Gyrs, with clusters in late-type spirals having a younger luminosity-weighted mean age than those in early-type spirals. The stellar populations of the clusters are generally best fit as a mixture of populations of different ages, indicating that star formation is an ongoing process in these clusters. The average cluster mass is smaller in late-type spirals than in early-type spirals. The cluster mass correlates strongly with the luminosity of the host galaxy bulge, with the same slope as the well-known correlation between supermassive black hole mass and bulge luminosity. I discuss these results in the context of models for the formation and evolution of both nuclear star clusters and black holes in galaxy centers.